读书人

Collections类中的reverseOrder方法解

发布时间: 2012-01-31 21:28:41 作者: rapoo

Collections类中的reverseOrder方法
我在LinkedList类中添加了引用类型的元素,使用Collections类中的reverseOrder方法反向排序,并迭代输出时报错,我想是不是我添加的是引用类型,程序并不能找出比较规则,所以我在下面又写了一个Comparator接口的实现类,想通过这个比较器设定一下规则,写完后又发现这个比较器作为参数不知道怎么传给LinkedList,因为LinkedList构造方法中没有传入Comparator类型的,不像TreeSet构造方法可以传Comparator类型。说的有点乱,请问怎么解决啊,可以复制代码运行一下,谢谢啦。
public class CollectonsTest {
public static void main(String[] args) {
LinkedList list = new LinkedList();

list.add(new Student(10));
list.add(new Student(20));
list.add(new Student(30));
list.add(new Student(40));

Comparator com = Collections.reverseOrder();
Collections.sort(list, com);

for(Iterator it = list.iterator();it.hasNext();){
Student stu = (Student)it.next();
System.out.println(stu.score);
}
}
}
class Student{
int score;
Student(int score){
this.score = score;
}
}
class MyComparator implements Comparator{
@Override
public int compare(Object o1, Object o2) {
Student s1 = (Student)o1;
Student s2 = (Student)o2;
return s1.score - s2.score;
}
}

[解决办法]

Java code
public class CollectonsTest {    public static void main(String[] args) {        LinkedList<Student> list = new LinkedList<Student>();        list.add(new Student(10));        list.add(new Student(20));        list.add(new Student(30));        list.add(new Student(40));        Comparator<Student> com = Collections.reverseOrder();        Collections.sort(list, com);        for (Iterator<Student> it = list.iterator(); it.hasNext();) {            Student stu = (Student) it.next();            System.out.println(stu.score);        }    }}class Student implements Comparable<Student>{    int score;    Student(int score) {        this.score = score;    }    @Override    public int compareTo(Student s) {        return this.score - s.score;    }} 

读书人网 >J2SE开发

热点推荐